I have to include my Big Stick. It has an inverted dihedral brace which isn't enough. It does need more to cancel roll.

If you don't want to cut your wing apart, you can add downward end plates as shown on a Little Stick. These add anhedral effect, cancelling adverse roll. The original Little Stick is shown without plates. I added lite ply plates, hanging down 1 1/2". These were lined off in 1/4" spaces. I flew and it rolled opposite to rudder. I then trimmed off 1/4" with some Craftsman shears and flew again. At 3/4 inch, the roll was pretty much killed. That's the way they are now. I use this plane to break in smaller engines, .20-.36.